You can use UFT Tool feature "Data Table" for Creating Test Data and connect to UFT Test Script,
Or
Using VBScript FileSystemObject Model you can import Test Data from an External Text File (Notepad) and connect to UFT Test Script
Or
Using VBScript Excel Application Object Model you can import Test Data from an External Excel File and connect to UFT Test Script
Or
Using VBScript Database Objects you can import Test Data from an External Database file and connect to UFT Test Script

If you want use Text File/Flat File as resource then use VBScript FileSystemObject as resource (Test Data File)
Or
Use Excel Application Object for Excel Files
Or
use Database Objects for Database Files.

Note: Tryto use Excel for Data Driven Testing, It is more flexible than others.